nmap"Service detection is correct 99% of the time and does what it should do perfectly. Best thing to use when diagnosing network security/issues on your LAN. Also a great addition to help finding trojans running on a windows computer, can fingerprint malware such as conficker etc. Top quality tool."

transmission"The first bittorrent client i ever used when i first moved to Linux/BSD, it was the best then, and is still the best now."

emesene"Its just like the windows counter-part with zero adverts. It has great plugins for music, msnplus colour support and other useful extensions."